The acetylcholine receptor (AchR) of the post-synaptic membrane is of considerable biological importance as the site of action of a number of pharmacological agents and toxins, and changes in the post-synaptic neuromuscular junction may be significant in disease processes such as muscular dystrophy. Because of the importance of the AchR, attempts are being made to isolate and purify this receptor from such sources as electric eel electroplax, cerebral cortex, and in Dr. Barnard's laboratory, rat diaphragm. Isolation is based upon extraction with Triton X-100 and gel filtration on Sepharose columns using H3-acetylated alpha-bungarotoxin as a marker. The first purpose of this proposal would therefore be to accelerate this effort to isolate and purify the acetylcholine receptor site. The second purpose would be to reconstitute the isolated receptor in model membrane systems such as phospholipid vesicles, Mueller-Rudin bilayers, and phospholipid monolayers. The failure to completely purify the receptor would not preclude successful reconstitution, as long as the original activity was retained. To determine that this was the case, pharmacological agents known to act on the receptor such as curare, carbamyl choline, and decamethonium would be tested with the intent of reproducing their effects In vivo. Since the receptor if successfully reconstituted would convey excitability upon these membrane systems, such parameters as membrane composition and surface charge density, monovalent and divalent ion concentrations and gradients, could be carefully regulated. Instrumentation presently available would allow measurements on a single conductance channel, providing information on the gating mechanism itself.